Bug in Clifford algebra multiplication

[tscrim]

This is a really bad associativity failure:

sage: r = ZZ['r'].fraction_field().gen()
sage: Q = QuadraticForm(r.parent(), 2, [0,r,0])
sage: C.<p,q> = CliffordAlgebra(Q)
sage: q * (p * q)
r*q
sage: (q * p) * q
-r*p*q + r^2

CC: @trevorkarn @fchapoton

Component: algebra

Keywords: Clifford

Author: Travis Scrimshaw

Branch/Commit: 4d56288

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/34707

[tscrim]

comment:1

The first answer is the correct answer.

[tscrim]

Author: Travis Scrimshaw

[tscrim]

comment:2

Okay, it is a very special case. It was checking that the first element of the LHS when the RHS was single monomial. In this example, the first returned term happened to be the constant term, so it thought it just needed to multiply the LHS by that scalar. So it actually is not so bad of a bug, just a special case.

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New commits:

4d56288

Checking that the RHS is a scalar of 1, not the LHS.

[tscrim]

Commit: 4d56288

[tscrim]

Branch: public/algebra/clifford_algebra_mult-34707

[fchapoton]

comment:3

ok if the bot comes back green

[fchapoton]

Reviewer: Frédéric Chapoton

[tscrim]

comment:5

Thank you! This has been around for a while and is a somewhat embarrassing bug from me...

[vbraun]

Changed branch from public/algebra/clifford_algebra_mult-34707 to 4d56288